Atrioventricular nodal reentrant tachycardia (AVNRT) is a regular supraventricular tachycardia (SVT) that results from the formation of a reentry circuit confined to the AV node and perinodal atrial tissue. Because of its abrupt onset and termination, AVNRT is categorized as a paroxysmal SVT (PSVT). As with the majority of SVTs, the QRS complex in AVNRT is usually narrow (ie, ≤120 msec), reflecting normal ventricular activation through the His-Purkinje system, although aberrant conduction (eg, underlying bundle branch block) can result in a wide QRS complex. (See "Clinical manifestations, diagnosis, and evaluation of narrow QRS complex tachycardias", section on 'Paroxysmal SVT'.)

AVNRT is the most common PSVT, accounting for nearly two-thirds of all PSVTs, and is more common in women compared with men [1-3]. AVNRT can present at any age, but as with AV reentrant tachycardia (AVRT) that involves an accessory pathway, it is more likely to begin in young adults. In a series of 231 patients with AVNRT, the mean age of symptom onset was 32 years, with two-thirds of cases beginning after the age of 20 [4].

ANATOMY AND PATHOPHYSIOLOGY

The physiologic substrate for AVNRT involves dual electrical pathways in or near the AV node (table 1) [5,6]. The arrhythmia usually develops in hearts that are otherwise normal, although it can also occur in the presence of underlying structural heart disease [7,8]. A more detailed discussion of the electrophysiology of AVNRT can be found in published reviews [5,6,9,10]. (See 'Dual AV nodal physiology' below.)

Anatomy — The exact anatomic distribution of these pathways is uncertain. Koch's triangle is bounded by the tricuspid ring and the tendon of Todoro, which bracket the coronary sinus at the base of the triangle and are in close proximity forming the apex near the His bundle at the membranous septum (figure 1 and figure 2) [5,11]. As an approximation, Koch's triangle can be divided into thirds:

To continue reading this article, you must log in with your personal, hospital,
or group practice subscription. For more information or to purchase a personal subscription, click below on
the option that best describes you: